Should hard coat anodizing be sealed?

Generally, when hard coat anodizing is applied for wear resistance, the coating is not sealed (except for PTFE seals), which is the default in most specifications. On the other hand, if corrosion resistance or a combination of corrosion and abrasion resistance is the primary purpose, the hard coat anodizing should be sealed. In general, all stained hard coat anodizing will require sealing to ensure the dye will not fade or bleach. Sealing can be accomplished with deionized water, sodium dichromate, nickel acetate, PTFE, or a combination of two or more of these.